Manufacture of lead and zinc alloys



Patented May'gl, 1932 7 UNITED STATES PATENT OFFICE JESSE OATMANBETTERTON, 01? OMAHA, NEBRASKA, ASSIGNOR TO AMERICAN SMELT ING ANDREFINING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY NoDrawing. Application filed November This invention relates to aprocessof forming alloys, and more particularly to a process of forming alloysof lead, zinc, magnesium and the alkaline earth metals in which any 5 orall of the above metals are present in any the alkaline earth metals orcombinations thereof which is carried out at sufficiently lowtemperatures to permit the use of standard apparatus.

In accordance with the invention a reagent is added to a bath of lead orzinc under a 'the broad spirit and scope of the invention. "In thefollowing description and in the claims the various steps in the processand the details comprising the invention will be chloride cover slagunder such conditions that the lead or zinc forms an alloy with themetal of the reagent or reacts with a metal of the slag which is throwninto the bath by means of the reagent. The slag in the above reactionso'that the process may be carried out at a low temperature and with theuse of standard apparatus.

- The invention also consists in'certain new and original features ofconstruction and combinations of parts hereinafter set forth andclaimed.

Although the novel features which are believed to be characteristic ofthis invention will be particularly pointed out in the claims appendedhereto, the invention itself, as to its objects and advantages, the modeof its operation and the manner of its organization may be betterunderstood by referring to the following descriptionin which aparticular commercial embodiment thereof is disclosed. It will beunderstood, however, that the processes and the steps thereof'may bemodified in various respects without departing from identifiedbyspecific names for convenience application as the art will permit.

but they are intended to be as generic in theirmnnraorunn or LEAD ANDzmc aLLoYs 1, 1930. Serial N0. 492,640.

In carrying on the process a bathof one alloy metal, for example, leador zinc is formed to which is added a cover slag of sodium chloridetogether with calcium chloride or a chloride of the metal or metalswhich it is desired to alloy with the bath, and which for ease ofdescription will be termed the alloy forming metals. The bath ismaintained at a temperature at which the slag is molten and calciumcarbide or a carbide of the alloy forming metal is added thereto.

The slag serves to dissolve any oxide coating which may be formed on thecarbide whereby it is permitted to come into intimate contact with thebath, and to prevent oxidation of the metals during the ensuingreaction. An alloy is then formed either from the metal of the carbideor from the metals of the slag which is thrown down by reaction with thecarbide. The particular metal which is thusv alloyed depends upon thevarious metalsemployed for the slag and for the carbide and theirrelative positions in electro-motive series.

For example, in alloying zinc with lead a slag of zinc chloride andsodium chloride would be employed and calcium carbide would be'used asthe reagent. The calcium carbide then reacts with the zinc chlorideeither directly according to Equation (1),

- thus producing metallic zinc which alloys with the lead for theproduction ofv a leadzinc alloy, or through the formation of anintermediate compound, liberating zinc and forming calcium chloride andfree carbon thereby throwing the zinc into the lead and forming alead-Zinc alloy in accordance with Equations (2). The sodium chlorideserves to reduce the melting point of the slag where by the abovereactions may be efiiciently carried ou In forming alloys of lead andmagnesium,

for example, a magnesiumchloride slagis used in place of the zincchloride slag above.

mentioned and a corresponding reaction takes with the metals,

place, throwing down the magnesium and producing a magnesium-lead alloy.

The magnesium-lead alloy may also be formed in still another method byusing a calcium chloride, sodium chloride slag and introducing themagnesium into the bath as a magnesium carbide. The magnesium carbidewill then ,be dissolved in the bath. releasing carbon and magnesium andcausing the latter to alloy with the lead.

The slag will be inert to the magnesium inasmuch as magnesium is lowerin the electromotive series than calcium.

Alloys of lead with the various alkaline earth metals may be obtained byany of the above methods by substituting the appropriate slags andcarbides. Calcium which is high in the electro-motive series is alloyeddirectly from the carbide with the use of a calcium chloride, sodiumchloride cover. The other alkaline earth metals may be alloyed from thecarbide thereof provided a cover slag which is inert to those metals isemployed or they may be alloyed from a chloride slag containing themetals provide a carbide is employed which stands higher in theelectro-motive series than the metal. Thus, barium may be alloyeddirectly from barium carbide with the use of a slag of calcium chlorideand sodium chloride (BaC =Ba+2C) or the barium may be alloyed from aslag of bariumchloride and sodium chloride with the use of calciumcarbide as the reagent. (BaCL, CaC CaCl +Ba+2C) Alloys of magnesium andthe alkaline earth metals with zinc'may be formed in a c0rrespondingmanner using a zinc bath and the particular chloride slag and carbidereagent which are adapted to bring about the suitable reaction. It willbe noted that the metal of the alloy is obtained from the carbidereagent, unless this reagent is capable of reacting with the slag torelease the metal of the,slag. Consequently, when the metal of thecarbide is higher in the electro-motive series than the metal of theslag, for example, a calcium carbide reagent and a zinc chloride slag,the carbide metal will react with the chloride and combine with thechlorine therefrom to release the metal of the slag which becomesalloyed with the bath. It is obvious, therefore, that by properlyselecting the reagent and the slag any desired alloy of the abovementioned metals may be formed desired proportions.

The slag acts to dissolve any oxide which may be formed onthe surface ofthe carpresent in substantially any actionis more efiiciently carriedout. Furthermore, the presence of the sodium chloride reduces themelting point of the slag to such value that comparatively lowtemperatures can be employed and standard apparatus can be used withoutinjury.

As a specific example of a manner in which the present process may becarried out, a quantity of lead or zinc may be applied to a standardlead melting kettle, as for'ekample. a kettle having 16 tons capacityand the temperature raised sufliciently to melt the lead or zinc andform a bath. Temperatures of 535 C. to 7 C. are usually suitable forthis pur pose. The kettle may, if desired, be covered mechanically forthe purpose of conserving heat and for preventing therfinal alloy fromcoming into. contact with air and suitable stirring means may beincorporated for agitating the bath and forming an intimate mixture ofthe bath and the reagents.

A dissolving cover slag is then applied to the surface of the bath.-This slag consists of calcium chloride or a chloride of the alloyforming metal or metals, together with so dium chloride. Calcium carbideor a carbide of the alloy forming metal is then added to the bath andrapidly stirred therein.

These carbides pass through the slag before coming into intimate contactwith the bath.

Preferably the cover slag is dehydrated before being applied to the bathinasmuch as completely dehydrated chlorides react more efiiciently withthe carbides which aresubsequently added to the bath. Dehydration,

may be accomplished by melting the chlorides and heating the same to atemperature of 1200 F. to 1300 F, At this temperature the mass iscompletely liquefied and a large portion of the water escapes as steam.A quantity of carbide, such as calcium carbide, representing from 5% to15% of the weight of the fused chlorides is then added and the mixtureis stirred by a suitable mixing machine. The carbide then reacts withthe water of combination forming acetylene gas which escapes andcompletes the dehydration.

ing slag is particularly. effective and completely cleans the surface ofthe carbide particles, whereby a full and complete surface contact isobtained between these particles and the molten bath. Under theseconditions the bath will substantially decompose the carbides at thetemperature range above men ter thereof. The carbides are then added tothis vortex and are rapidly drawn under the surface of the molten'bath,whereby unneces- The action of the above mentioned dissolvsary exposureto the air is avoided and their tendency to oxidize is materiallydecreased. After the desired alloy has been formed, the slag may beremoved from the bath in-any suitable manner. This may be accomplishedeither by skimming the slag or by pumping or tapping the alloy from thekettle. a It is obvious that the percentages of the various metals maybe varied within wide limits and that any combination of the abovementioned metals may be formed into an alloy by suitable selection ofthe metal of the skilled in the art without departing from the spirit ofthe invention.

What is claimed is:

1. The" process of forming metal alloys having relatively low meltingpoints which comprises forming a bath of one of said metals with arelatively low melting point, applying to said bath a low melting pointslag containing a chloride of the other of said metals and "introducingto said bath a reagent capable of reacting with said chloride forreleasing said other metal and causing the same to enter said bath andform an alloy therewith.

2. The process of vforming metal alloys having relatively low meltingpoints whichv comprises forming a bath of one of said metals with arelatively low melting point, applying thereto a low melting point slagcontaining a chloride of the other of said metals and adding to saidbath a reagent comprising a metal carbide capable ofreacting with saidslag to release the metal thereof and cause the same to enter said bathand alloy therewith. v I

3. The process of forming metal alloys having relatively low meltingpoints which comprises forming a bath of one of said metals with arelatively low melting point,

applying thereto a low melting point slag containing a chloride of theother of said metals and sodium chloride, adding to said bath a reagentcomprising a metal carbide capable of reacting with said slag to re easethe metal thereof and cause the same to enter said bath and alloytherewith, said sodium chloride acting to reduce the melting point ofthe slag whereby the process can be carried on at lower temperatures.

4. The process of forming an alloy of lead with a metal of the groupcomprising zinc,

magnesium and the alkaline earth metals, which comprises adding to'abath of lead a slag containing a chloride of the metal to be alloyedtherewith and applying to said bath a reagent capable of reacting withsaid chloride to release said metal and causethesame to ellllter saidbath and become alloyed therewit 5. The process of forming an alloy oflead with a metal of the group comprising zinc,

magnesium and the alkaline. earth metals,

which comprises adding to a bath of lead a slag containing a chloride ofthe metal to be alloyed therewith and applying to said bath a reagentcomprising calcium carbide and maintaining said bath at a suitabletemperature to permit said carbide to react with said slag, whereby themetal of the slag is released and caused to enter said bath and to alloytherewith.

6. The process of forming an alloy of lead with a metal of the groupcomprising, zinc,

magnesuim and the alkaline earth metals, which comprises adding to abath of lead a slag containing a chloride of themetal to be alloyedtherewith together with sodium chloride, applying to said bath a reagentcapable of reacting with said chloride torelease said metal and causethe same to enter said bath and become alloyed therewith, said sodiumchloride serving to reduce the melting point of the slag whereby theprocess can be carried on at lower temperatures.

7. The processof forming alloys of lead with magnesium, zinc'and thealkaline earth metals which comprises forming a bath of molten lead at atemperature range of substTantially 535 C. to 760 0., adding to thesurface of said bath a slag containing a chloride of the metal to bealloyed therewith and applyingcalcium carbide to said bath whilemaintaining the bath at the above temperature, whereby said calciumcarbide reacts with said slag to release the metal therefrom and tocausethe same to enter said bath and become alloyed therewith.

8. The process of forming an alloy of lead with magnesium, zinc or thealkaline earth' metals which comprises forming a bath of lead and addingthereto a slag containing the magnesium or alkaline earth metal in thechloride form, together with sodium chloride, maintaining the bath at atemperature at which said slag is molten and adding a reagent to saidbath capable of reacting with the metal chloride to release the metalthere from, whereby said metal enters said bath and becomes alloyedtherewith.

9. The process of forming an alloy of zinc with magnesium or thealkaline earth metals which comprises forming a bath of zinc, addingthereto a slag comprising a chloride of the desired alloy metal, andadding to said bath a reagent capable of reacting with said chloride torelease said metal and permit the same to enter said bath and alloytherewith. 10. The process of forming an alloy of zinc with a metal ofthe group comprising magnesium and the alkaline earth metals, which 5comprises adding to a bath of zinc a slag containlng a chloride of themetal to be alloyed therewith and applying to said bath a reagentcomprising calcium carbide and maintaining said bath at a suitabletemperature to permit said carbide to react with said slag,

whereby the metal of the slag is released and caused to enter said bathand to alloy therewith.

11. The process of forming an alloy of zinc with magnesium or thealkaline earth metals which COIIIPHSGS forming a bath of zinc and addingthereto a slag containing magnesium or the alkaline earth metals in thechloride form, together with. sodium chloride, maintaining the bath at atemperature at which said slag is molten, adding a reagent to said bathcapable of reacting with the metal chloride to release the metaltherefrom, whereby i said metal enters said bath and becomes alloyedtherewith. m

12. The process of forming alloys of zinc with magnesium and thealkaline earth metals which comprises forming a bath of molten zinc,addirfg to the surfaceof said ath a slag containing a chloride of themeta to be alloyed therewith and applying calcium carbide to said bath,whereby said calcium carbide reacts with said slag to release the metaltherefrom and to cause thesame to enter said bath and become alloyedtherewith. In testimony whereof I have hereunto set myhand.

JESSE OATMAN BETTERTON.

